Abstract: The invention relates to a system for controlling power consumption at a user of electric power, especially a dwelling supplies with power from a power plant. The invention is characterized in that the control unit is a main unit arranged to control the power consumption also based on an estimate of a historical consumption pattern at the user, so that the instantaneous consumption is reduced both in the periods in which the power load at the user is highest, and in the periods in which the historical consumption pattern of the user dictates that there is a high load, and that the main unit user is arranged to distribute the power consumption by means of a random function distributing the connection of the power consuming units over a given time interval, the random function being independent of energy plants and other users.